In new bodies, brain cells find longer lives

Transplanted mouse neurons survive for twice the lifespan of a mouse.

The search for the fountain of youth is nothing new; we humans have long been trying to lengthen our lifespans. In recent years, science and medicine have made great strides in increasing how long we live. The average life expectancy of an American is now more than 78 years, up nearly a decade since 1960. But as we live longer and longer, what will happen to the cells that compose our brains? If we are able to live to 120, 150, or longer, can our brain cells survive that long too? Or in the future, will our neurons die long before we do, leaving our brains depleted?

To start answering this question, three Italian researchers carried out a series of transplant experiments and found that neurons can last far longer than the organisms in which they originated. In this week’s issue of PNAS, the scientists describe their research, which suggests neuron survival may be more flexible than previously thought.

The researchers chose to work with mice and rats. The two animals are similar in many regards, but they differ substantially in their life expectancy (rats survive far longer than mice). By transplanting cells between these two species, the scientists could determine whether neurons have a pre-programmed lifespan based on genetics or whether they have more plasticity.

They took “neuroglial precursors”—cells that develop into neurons—from mice bred to express a fluorescent protein and then transplanted these cells into rat embryos. Thanks to the fluorescence, the researchers could visibly track the transplanted neurons as the rats aged, keeping an eye on the cells' development, status, and survival.

The researchers focused on a certain type of neuron, called a Purkinje cell, that plays a role in motor function and movement. These large neurons tend to deteriorate and die off as animals age. Mice, for instance, lose as many as 40 percent of their Purkinje cells by the time they die.

The mouse-donated cells took hold in 20 of the 59 rats, developing in these animals just as normal rat neurons would. However, they retained many of the characteristics of mouse neurons, such as shape and size. Just as they would have under normal circumstances, the transplanted brain cells deteriorated somewhat, slowly losing dendritic spines.

But inside the rats’ brains, the cells didn’t die off after 18 months, when most of the mice they originated in would have died. Instead, the neurons survived as long as the host rats did, up to 36 months. In other words, inside a rat’s brain, the donated neurons survived for the lifespan of two average mice.

This discovery suggests brain cell survival isn’t pre-programmed by genetics—or at least it isn’t completely tied to the lifespan of the organism where the cells originate. Instead, their survival may depend on the microenvironment of the organism that they inhabit. Neuron aging and survival appear to be controlled by two processes which—while related—may be separable. But there's much more to learn, since we don't yet know much about either of these processes.

Despite the unknowns, this is good news for those of us who want to live long past 78 years (and still be coherent enough to enjoy it). The research suggests that scientists could potentially extend our lifespans dramatically without leaving us devoid of brain cells.

22 Reader Comments

I'm not sure what quality of life these mice had though compared to the rats. Considering they were just lab animals, we may never know what the real impact of transplanting those cells would have on what those rats felt.

In my experience, mice tend to be more hyperactive than rats too. I wonder if there is still a utility trade-off, for example since the neurons studied control movement, what if the mice burn up their neurons faster because they get twice as much use in those first 18 months as rats do?

Of course, everyone here is going to go on about transplanting their brains into various other things. The more immediate utility of this research would be towards researching Alzheimers disease. Why do brain cells have the ability to outlast their environments in some cases, but deteriorate in their original environment? The import of this research is that Alzheimers is not directly related to aging, but we become more susceptible to it as we age.

Not surprised. Apart from Alzheimer and dementia, the brain has relatively few age related life threatening deterioration. The bottleneck for aging (common cause for old age death) seems to be the heart (heart attacks) and the blood circulation system (even seizures is due to blood vessel blockage, bursted arteries, etc) and maybe cancer.

Sorry if I miss read but is it stated anywhere that this is different in brain cells or nerons than any other cells?, For example would mouse colon cells live beyond the expected mouse lifespan in the ass of a rat?I mean honestly, I'm pretty certain programmed cell death is a system based phenomenon, hence why the tendacy towards cancer is so tissue type agnostic. At anytimeit seems logical there's a sort term advantage for indivisual cells not to die and rather Its for the the health of the surrounding mass, but still genetical related, of other cells that induces indivisual cells to intentionally cease function. So yeah, ... Sucessfully transplant a few dozen of my ass cells into an long lived species like the giant turtle or even a sea enmity and its as unlikely my ass cells wound spontaniously die when i die as it is they will experiance diarrhea the same morning after i order in Cheap thai food.Maybe I'm being an idiot but I don't see in any way how this impacts some infantile delusion about imortality.

In my experience, mice tend to be more hyperactive than rats too. I wonder if there is still a utility trade-off, for example since the neurons studied control movement, what if the mice burn up their neurons faster because they get twice as much use in those first 18 months as rats do?

Interesting question, although when applied to single cells, particularly neurons, it becomes more complicated. There is a phenomenon called "excitotoxicity" which is where neurons are killed by excessive neurotransmitter stimulation. Conversely, a neuron that doesn't get enough stimulation from its connections can actually die, which is how some neurodegenerative diseases spread through the brain: Neurons first die in one area of the brain, then the neurons connected to them upstream become disconnected and die, an so on.

Not surprised. Apart from Alzheimer and dementia, the brain has relatively few age related life threatening deterioration. The bottleneck for aging (common cause for old age death) seems to be the heart (heart attacks) and the blood circulation system (even seizures is due to blood vessel blockage, bursted arteries, etc) and maybe cancer.

To follow on from your point, there's a link here (http://www.guardian.co.uk/news/datablog ... death-2011) visualizing the incidence and types of things people were dying of in the UK in 2011. The late onset neurological conditions are mainly Alzheimer's, Parkinson's, Motor Neuron Disease and Multiple Sclerosis. Although they are classified separately from from vascular dementias which outnumber Parkinson's fourfold, and separated from early onset neurodegenerative diseases.

If you kook at cryonics providers, just googled it and found Alcor, when you pay up to be frozen and preserved after death they generally just keep your brain not the whole body. Seems people have for a while now at least conceptually bought into brain cells remaining viable.

If you kook at cryonics providers, just googled it and found Alcor, when you pay up to be frozen and preserved after death they generally just keep your brain not the whole body. Seems people have for a while now at least conceptually bought into brain cells remaining viable.

Who ever dies of a dead brain? Sure brains go and you get dimentia, but dying of natural causes isn't "the brain failed". Usually, as I understand it, it is heart failure though not from a heart attack, then the brain dies due to lack of oxygen. In some people cardio/blood o2 levels may drop where the brain shuts down, but this isn't from neuron failure per se. This is from metabolic impairment.

Who ever dies of a dead brain? Sure brains go and you get dimentia, but dying of natural causes isn't "the brain failed". Usually, as I understand it, it is heart failure though not from a heart attack, then the brain dies due to lack of oxygen. In some people cardio/blood o2 levels may drop where the brain shuts down, but this isn't from neuron failure per se. This is from metabolic impairment.

You can die from a dead brain, for example, when your brain stem is damaged, either physically or by chronic degeneration. The brain stem controls autonomic functions such as heart rate, breathing rhythm, swallowing, temperature control etc.

Who ever dies of a dead brain? Sure brains go and you get dimentia, but dying of natural causes isn't "the brain failed". Usually, as I understand it, it is heart failure though not from a heart attack, then the brain dies due to lack of oxygen. In some people cardio/blood o2 levels may drop where the brain shuts down, but this isn't from neuron failure per se. This is from metabolic impairment.

You can die from a dead brain, for example, when your brain stem is damaged, either physically or by chronic degeneration. The brain stem controls autonomic functions such as heart rate, breathing rhythm, swallowing, temperature control etc.

Who ever dies of a dead brain? Sure brains go and you get dimentia, but dying of natural causes isn't "the brain failed". Usually, as I understand it, it is heart failure though not from a heart attack, then the brain dies due to lack of oxygen. In some people cardio/blood o2 levels may drop where the brain shuts down, but this isn't from neuron failure per se. This is from metabolic impairment.

You can die from a dead brain, for example, when your brain stem is damaged, either physically or by chronic degeneration. The brain stem controls autonomic functions such as heart rate, breathing rhythm, swallowing, temperature control etc.

I'll concede your second point - I'm struggling to find any example of late-onset neurodegenerative disease where the brain stem damage is the direct cause of death. However I don't understand what you mean when you say "brain disconnect"?

Kate Shaw Yoshida / Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas.